Biasing control for fuel injection system



Nov. 24, 1959 H. M. GAMMON BIASING CONTROL FOR FUEL INJECTION SYSTEMFiled Feb. 20, 1956 2 Sheets-Sheet 1 .57 V E .27 TE z" //0 WA RD M624M10 Hiya.

Nov. 24; I H. M. GAMMON BJIIASING CONTROL FOR FUEL INJECTION SYSTEMFiled- Fe bQ 20, 1956 2 Sheets-Sheet 2 f'YI EJ-Z 2722- flaw/mo 44.@AMMO/V moi;

United States Patent i BIASING comm. FOR FUEL INJECTION SYSTEM Howard M.Gammon, Chardon, Ohio, assignor to Thompson Ramo Wooldridge, Inc., acorporation of Ohio Application February 20, 1956, Serial No. 566,461

2 Claims. (Cl. 123-140) engine should be varied in response to theamount 1 of air admitted to the combustion chamber in order to achieveperfect combustion. In many types of fuel injection control systems forinternal combustion engines of the piston type, the quantity of fuelthat is metered to the engine is regulated in accordance with inductionsystem pressure that is measured by a sensing device in the controlmechanism. In some cases, the fuel control mechanism does not obtain apressure signal from the induction system instantaneously, wherein arapid increase in induction system pressure results in a temporaryleaning of the fuel-air mixture ratio until that time when the sensingdevice obtains an induction system pressure change signal. Such atemporary leaning of the mixture ratio is undesirable, particularlybecause it momentarily reduces the power and efiiciency of the engine.

In a carbureted engine, the same problem exists but is overcome by anaccelerator pump or plunger that responds to the rapid change ofthrottle motion by injecting extra fuel into the induction systemthereby avoiding a gas leaning out of the mixture. Some fuel injectionsystems utilize similar devices to displace extra fuel directly into theintake manifold or internally overriding the con trol linkage to createa higher rate of fuel displacement for injection. For the most part,these systems have not been altogether satisfactory and have includedmore or less complicated mechanisms.

Accordingly, it is an object of this invention to provide an improveddevice for regulating the quantity of fuelmetered to internal combustionengines that obviates the above named difficulties, and automaticallyregulates the fuel feed as to secure at all times proper combustionmixtures.

Another object of this invention is to provide a simply constructedmechanism for use with fuel injection systems which instantaneouslyprovides momentary increases in metered fuel upon demand from a rapidincrease in in duction system pressure.

A further object of this invention resides inthe provision of a biasingcontrol for fuel injection systems associated with internal combustionengines which instantaneously reduces the quantity of metered fuel at atime when the throttle linkage is moved suddenly to close the butterflyvalve in the induction system manifold, thereby conserving fuel andminimizing the quantity of unburned hydro-carbons that are expelled fromthe engine exhaust system.

Other objects, features and advantages of the invention will be apparentfrom the following detailed description of the accompanying sheets ofdrawings, wherein like ref- 2,914,055 Patented Nov. 24, 1959 ice erencenumerals refer to like parts, in which, on the drawrugs:

Figure 1 is a diagrammatic view of a fuel control system embodying thepresent invention;

Figure 2 is a diagrammatic view of a fuel control system embodying adifferent form of the invention;

Figure 3 is a diagrammatic view of a fuel control system embodying astill different form of the invention; and

Figure 4 is a diagrammatic view of a fuel control system embodyinganother form of the invention.

As shown on the drawings:

, Referring now to Figure l, 10 represents an air intake manifold of aninternal combustion engine having a fuel injection system (not shown)for metering fuel to the combustion chambers thereof. A butterfly valve10a is interconnected with the throttle linkage of the engine forcontrolling the air pressure in the manifold. The manifold operatesunder a negative pressure or a vacuum. As is well known in fuelinjection systems, a plurality of injectors are provided, one for eachcombustion chamber wherein the amount of fuel metered at each injectionis regulated by a metering control through rod 11. This metering controlis augmented by a pressure sensing element 12 responsive to enginemanifold pressure. In the present invention, a biasing control element17 is connected to the pressure sensing element to bias the function ofsaid sensing element.

Actuation of the injector control rod 11 is in response to a pressuresensing device 12 having a casing or housing 13 of any suitableconfiguration. The control rod 11 extends through a bore in one end ofthe housing 13 and has its free end connected to a rigid portion of aflexible bellows 14 or other pressure responsive element in a pressurechamber 15 of the casing 13. The inside of the bellows 14 communicateswith the atmosphere through a series of apertures 16 (only one shown)formed in the end of the housing 13 sothat any pressure above or belowatmospheric pressure in the chamber 15 acts on the bellows 14 and thecontrol rod 11. The contro-lrod '11 operates the fuel injector shownschematically at 40, which maybe of any desired construction. Movementof the control rod 11 in the direction marked Ace. will operate theinjector to feed more fuel to the engine for acceleration and movementin the direction marked Dec. will de' crease the supply of fuel.

During the running of an engine having this fuel control system, thechamber 15 of the pressure sensing device is subjected to the pressurein the manifold 10, and.

is thusly in communication with the manifold through a biasing element17. Hence, the control rod 11 normally responds to the variations ininduction system pressure. The biasing element 17 includes a hollowcylinder 18 connected at one end to the chamber 15 of the pressuresensing element 12 through a suitable pipe or conduit 19, and at theother end to the intake manifold 10 through a suitable pipe or conduit20. A piston 21 is slidably received within the cylinder bore andprovided with a clearance 22 of predetermined dimension therewith.Connected to the piston 21 is a piston rod 23 which extends through oneend of the cylinder 18 to be connected to the throttle linkage and footaccelerator pedal of the engine. An accelerator pedal 42 is shownpivoted at 43 on a support 41 for manual operation for operating thethrottle butterfly 10a and the piston 21. The pedal 42 v is connected toan arm 53 of a bell crank 45 by a link is transmitted to the piston byconnecting the piston rod 23 to the arm 52 of the bell crank.

In operation, when the foot pedal is suddenly pushed down toward itssupport 41 in the direction to accelerate the engine, the butterflyvalve a will open to permit greater air flowage within the manifold 10,thereby decreasing the vacuum in the system including cylinder 18 andchamber 15. The piston 21 will be mechanically advanced by theaccelerator pedal linkage towards the end 18a of the cylinder 18 whichis in communication with the pressure sensing mechanism 12. This actionon the piston instantaneously provides a compression of gases ahead ofthe piston that is immediately sensed by the pressure sensing mechanism12, the positive pressure created by the sensing element subtractingfrom the vacuum in the manifold thereby collapsing the bellows 14 andcausing the control rod 11 to be actuated for increasing the flow ofmetered fuel sent to the engine combustion chambers.

Due to the clearance 22 between the loosely fitting piston 21 and thecylinder bore, pressure on opposite sides of the piston 21 will equalizein a predetermined period of time to permit the sensing mechanism torespond to the manifold pressure. During normal operation, the clearancebetween the piston and the cylinder is sufficiently great so that smallvariances in manifold pressure will be registered almost instantaneouslyon the pressure sensing mechanism of the injector control.Alternatively, the piston could make sealing contact with the cylinderbore and be provided with a metered passageway therethrough. Hence, thebiasing signal set up in the biasing element 17 by accelerator pedalmovement and transmitted to the pressure sensing mechanism 12instantaneously causes the fuel injection control to inject a largeramount of fuel than would normally be injected and thereby satisfies theimmediate demand for accelerations and enrichment of the air-fuelmixture.

After a short acceleration time, pressures on both sides of the piston21 will equalize and the fuel injector will be controlled by pressure inthe manifold 10 as controlled by the factors of the position of thethrottle valve 10a and the load on the engine as reflected in enginespeed variation.

For deceleration conditions, should the throttle linkage be movedsuddenly in the direction to close the butterfiy valve, the piston 21will be suddenly moved to the end 18b of the cylinder 18which.communicates with the manifold thereby reducing the pressure inthe end of the cylinder that communicates with the pressure sensingmechanism 12 and, thusly, reducing the quantity of metered fuel to befed to the engine by movement of the injector control rod 11. Thisbiasing control, therefore, eliminates the inherent time delay in mostfuel injection systems.

It will be understood that the relationship of the control rod 11 to thefuel injector and the relationship of the accelerator pedal linkage tothe piston rod 23 and valve 10a, as shown and described in connectionwith Figure 1, will be the same in the forms shown in Figures 2, 3 and4, and, therefore, need only be shown and described in detail inconnection with Figure 1.

In Figure 2, a different form of the invention is illustrated, whichlargely differs from the embodiment shown in Figure 1 in that themanifold 10 is in direct communication with the chamber 15 of thepressure sensing mechanism 12 through a pipe or conduit 24. Also, theend 18b of the biasing element cylinder 18 towards which the piston 21advances during deceleration of the engine is connected to the interiorof the bellows 14 by a conduit or pipe 25, while the other end 18a ofthe cylinder is in communication with the atmosphere through a port 26.The operation of this embodiment is similar to that of the embodiment inFigure 1, except that depression of the accelerator pedal causes thepiston 21 in the biasing element 17 to advance towards the end 18a ofthe cylinder 18 in which the atmospheric port 26 is positioned. Thisrapid acceleration will cause the inside of the bellows to be subjectedto a reduced pressure which will instantaneously cause actuation of thecontrol rod 11 to inject a larger amount of fuel into the enginecylinders. During deceleration, the piston 21 will be moved toward theend 18b of the cylinder 18, having the conduit 25 connected thereto, forexpanding the bellows 14 and actuating the control rod toinstantaneously reduce the quantity of metered fuel to be fed to theengine. Increases and decreases in vacuum in the manifold 10 willlikewise expand and compress the bellows 14 to control the fuel supplyduring normal operation when the accelerator pedal and throtle valve 10aare not moved.

Referring now to Figure 3, the biasing element 17 is shown associatedwith a different arrangement. This arrangement is substantiallyidentical with that in Figure 1, except that the pressure sensingelement 12 represents a specific fuel injection control system, namelythe American-Bosch system. Inasmuch as the detailed construction andoperation of this control system are well known in the prior art, it isnot necessary to explain too much detail. However, for purposes ofclarity, the system includes a hollow cylindrical shell 27 open at oneend and slidably receiving a piston 28 having a port 29 in one end andbeing biased towards the open end by a pair of springs 30. The piston 28is hollow and slidably received therein is a second piston 31 which isconnected to the injection control rod 11 and biased away from the port29 by a spring 32.

Another embodiment of the invention, shown in Figure 4, is basically thesame as that shown in Figure 2 in that the biasing element is disposedbetween the pressure sensing mechanism and atmosphere, except that thebiasing element and the pressure sensing mechanism are enclosed Within acommon housing or casing 33. In this embodiment, the common casing 33includes a hollow cylindrical section 33a at one end and a diametricallyreduced hollow cylindrical portion 33b at the other end.

The larger housing section 33a encloses the pressure sensing mechanism,while the smaller housing section 3312 encloses the biasing element. Thecontrol rod 11 for the injectors is connected to a piston 34 slidablyreceived within the housing section 33a and normally biased in thedirection of the control rod 11 by a spring 35. To receive a signal fromthe biasing element, a piston 36 slidably received within the bore ofthe biasing element cylinder in the housing section 33b is directlyconnected to the piston 34 by a rod 37. A chamber 38 is defined betweenthe pistons 34 and 36 which more or less corresponds to the chamber 15in the pressure sensing mechanism 12 of Figures 1 and 2, and isconnected to the manifold by a pipe or conduit 39.

The operation of this embodiment is substantially identical with theforegoing embodiment, wherein a rapid movement of the throttle linkageto accelerate the engine advances the piston 21 to compress the gaswithin the cylinder between it and the piston 36 of the pressure sensingmechanism. This signal generated by the compression of gases subjectsthe piston 36 to a pressure and causes it to slide axially towards thelarger housing section 33a, and since this piston is connected directlyto the control rod 11, it causes the fuel injection control to eject alarger amount of fuel into the engine. During normal operation, thepiston 34 is subjected to the manifold pressure through the line 39 foraccordingly adjusting the amount of fuel metered to the engine by theinjectors. The clearance 22 between the piston and the cylinder boreallows equalization of pressure on both sides of the piston 21 to equalthat of the atmosphere through the port 40.

From the foregoing, it is seen that the instant invention provides abiasing control for fuel injection systems which instantaneously causesmomentary increases or decreases in metered fuel to the engine uponrapid acceleration or deceleration demands. 7

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention, but it is understood that this application is to be limitedonly by the scope of the appended claims.

I claim as my invention:

1. In an internal combustion engine having a fuel injection system and apressure sensing mechanism responsive to the manifold pressure forcontrolling the quantity of fuel metered to the engine by the system,the improvement of means for transmitting a pressure signal to saidmechanism in response to rapid acceleration or deceleration of saidengine for providing momentary increases or decreases in metered fuel tothe engine, said means comprising a cylinder having a piston slidabletherein and connected to the throttle linkage of said engine wherebyrelative movement between the piston and cylinder is caused withmovement of the throttle linkage, one end of said cylinder communicatingwith said pressure sensing mechanism, said piston sized to provide aclearance of predetermined dimension with the bore of said cylin-:

der, and the other end of said cylinder communicating with the engineintake manifold.

2. The combination with an internal combustion engine of the injectiontype having an air intake manifold and a throttle valve therein, ofadjustable fuel injection means, a pressure sensing mechanism, a controlrod actuated by said mechanism and being connected to said injectionmeans, said sensing mechanism responding to the pressure in the intakemanifold, and signalling means between said sensing mechanism and saidair intake manifold, said signalling means comprising a cylinder havinga piston slidable therein and connected to said throttle valve, one endof said cylinder communicating with said sensing mechanism and saidother end communicating with said intake manifold, and means defining aleakage path around the end of the cylinder connected with said sensingmechanism so that a temporary signal will be generated.

References Cited in the file of this patent UNITED STATES PATENTS2,074,514 Muller Mar. 23, 1937 2,080,746 Schweizer May 18, 19372,189,475 Saur Feb. 6, 1940 2,794,432 Nystrom June 4, 1957 FOREIGNPATENTS 816,793 France May 10, 1937 378,233 Italy Jan. 26, 1940 572.787Great Britain Oct. 23, 1945

